Attack-resistant padlock

ABSTRACT

An attack-resistant padlock has a shackle of maraged steel, deadlocked in locked position by a pair of oppositely-moving bolts positively driven by a rotary throw member having specially-shaped driving lugs, which have long arcuate external faces tangent to transverse faces on the bolts to positively deadlock the bolts in locking position. The throw member is mounted in a retaining plate secured by engagement in a notch in the casing and by a shackle retaining plug which may be pinned in place, and is further supported by a filler block which reinforces the throw member legs and is held in place by the keyremovable lock core. The lock core is desirably secured not only by its normal key-actuated lug, but additionally by a keeper plate mounted in the bottom of a downward extension of the shackle-toe receiving bore. The invention is applicable both to shrouded and unshrounded padlocks.

[ 51 May 13, 1975 ATTACK-RESISTANT PADLOCK Inventors: Max L. Flack; William R. Foshee;

Ralph E. Le Tourneau, all of Indianapolis, Ind.

Best Lock Corporation, Indianapolis, Ind.

Filed: July 23, 1973 Appl. N0.: 381,925

Assignee:

References Cited UNITED STATES PATENTS 1,246,472 11/1917 Salvatore 70/38 A 3,605,458 9/1971 Best 70/49 FOREIGN PATENTS OR APPLICATIONS 402,044 9/1924 Germany 70/38 A Primary Examiner- -Robert L. Wolfe Attorney, Agent, or Firm -Trask, Jenkins & Hanley [57] ABSTRACT An attack-resistant padlock has a shackle of maraged steel, deadlocked in locked position by a pair of oppositely-moving bolts positively driven by a rotary throw member having specially-shaped driving lugs. which have long arcuate external faces tangent to transverse faces on the bolts to positively deadlock the bolts in locking position. The throw member is mounted in a retaining plate secured by engagement in a notch in the casing and by a shackle retaining plug which may be pinned in place, and is further supported by a filler block which reinforces the throw member legs and is held in place by the keyremovable lock core. The lock core is desirably secured not only by its normal key-actuated lug, but additionally by a keeper plate mounted in the bottom of a downward extension of the shackle-toe receiving bore. The invention is applicable both to shrouded and unshrounded padlocks.

15 Claims, 9 Drawing Figures PATENIED MY 1 31975 SHEE'! 10F 3 PATENTEB MAY I 31975 SHEET 3 OF 3 Fig 1 ATTACK-RESISTANT PADLOCK BACKGROUND OF THE INVENTION This invention relates to a padlock having improved attack-resistance, especially a padlock of the type ing on a truck, and does so both at normal temperatures and at cryogenic temperatures.

One method of attacking a padlock to produce unauthorized forced opening of the padlock is by hammering, either at normal temperatures or after cooling the padlock, as with liquid nitrogen, to a low temperature such as of the order of l50F. Such attack may have the effect of fracturing one or more parts, or of causing thrust or other stress on the shackle retaining bolts to release them and the shackle, or of breaking or loosening the locking means by which the shackle retaining plug is secured in place, or of directly or in consequence damaging or loosening the throw member and tumbler retaining plate so as to cause the tumblers to retract and release the shackle.

SUMMARY OF THE INVENTION The present invention greatly improves the ability of the padlock of the type described to withstand such forced entry attack. In accordance with the invention, the padlock has two oppositely moving bolts which deadlock into the toe and heel of the shackle, and these are positively driven both in projection and retraction BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention, and show two modifications of a preferred embodiment. In such drawings:

FIG. I is a vertical section ofa shrouded padlock embodying the invention, with a key-removable lock core mounted therein;

FIG. 2 is atop plan view of the shrouded padlock of FIG. 1;

FIG; 3 is a vertical section of an unshrouded padlock containing the same mechanism as that of FIG. 1, and

showing the structure with the lock core removed to movement by engagement with specially shaped lugs I shackle plug is secured by a known bayonet lock engagement with bosses onthe inner wall of the casing and may also be secured by a steel pin, to ensure its support for one end of the retaining plate in which the throw member ismounted. In addition, legs of the throw member are received in a filler plug which rein- .forces and supports them against distortion and which fills the space between the key-removable plug and the retaining plate so that such plate is supported by the core when the core is in place. For increased security, the core isdesirably secured not only by the known engagement of a retractable plug with retaining lugs in the side wall of the casing, but additionally by a keeper plate mounted at the bottom of an extension of the shackle-toe receiving bore in the padlock casing. The shackle used is desirably of maraged steel which retains its hardness and ductility, and especially its notch toughness, over a wide temperature range extending well down into the cryogenic temperatures.

The special shape of the throw member drive lugs provides external lug surfaces on an arc about the axis .of rotation of the throw member, which are engaged tangentially at a substanially dead-center position by a bolts surface normal to the direction of tumbler retraction movement so asto positively lock the bolts against retraction and prevent theigeneration 0f turningmoments on the throw member from force on the bolts, and such surfaces extend through long arcs ofjsay 30 so that they are operative over a range of throw member positions.

show the internal configuration of the lock casing; FIG. 4 is a perspective view of the key-removable lock core;

FIG. 5 is a section taken on the line 5-5 of FIG. 3, showing the bolts in locking positions;

FIG. 6 is like FIG. 5 but shows the bolts in retracted position; 1

FIG. 7 is a section taken on the line 77 of FIG. 3, showing the bolt retaining plate;

FIG. 8 is a section taken on the line 88 of FIG. 3, showing the transverse lugs in the casing which retain the shackle plug and the key-removable core; and

FIG. 9 is a bottom plan view of the lock of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S) The padlock shown in two modifications in the draw-- ings comprises a shackle l0 and a lock case 12. In FIGS. 1 and 2, the padlock is a high security padlock in which the lock case 12 has an upstanding shroud 14 at its upper end, extending along three sides of the case and shrouding the curved bight 17 of the shackle 10. As

shown in FIG. 2, the shrouded padlock is adapted for securing two locking bars 13 and 15 and for protecting the same from cutting or other forced entry attack. In FIG. 3, the shroud 14 is omitted and the lock case 12 is of conventional configuration. In both modifications, theinternal construction shown is the same.

The shackle 10 in each case is generally J-shaped bar with a toe leg 16, a bight l7 and a heel leg 18. The toe and heel legs 16 and 18 are provided with notches 20 for the reception bolts described below. The shackle is desirably made of a maraging steel, and processed by the conventional maraging process, so as to have improved hardness and especially toughness at extreme temperatures, both high temperatures. and especially low temperatures down to say l50F.

The lock case 12 in each case is an integral one-piece body formed with an end wall 22 having spaced parallel bores 24 and 26 for the reception of the legs 16 and 18 of the shackle. A lock cavity 28 is'formed in the opposite end of the case 12 for the reception of the locking mechanism. The cavity 28 is formed by boring three parallel overlapping bores 30, 32 and 34, and by subsequently milling away portions of the longitudinal ribs between the bores to form flat sides 36 and 38 but to leave inwardly projecting lugs 40 adjacent the outer end of the cavity and lugs 42 spaced inward from such outer lugs 40. The inner end of the cavity has a flat end face 44, and the right edge of the cavity is milled to form a groove 46 adjacent but spaced from the flat ward substantially to the bottom of the case, and overlaps the cavity bore 30. The leg 18 is formed with a peripheral groove 48 which leaves a continuous flange 49 at the end of the leg. Upward from such flange, the leg is milled on its inner face to provide an elongated clearance groove 50. The shackle is retained in place by a shackle retainer plug 52 which fits into the cavity bore 30 and is locked therein by a bayonet lock engagement of lugs 54 on such plug with the retaining lugs 42 and 40 between the cavity bores 30 and 32. For greater security, the plug is fixed by a pin 55 which in a shrouded case 12 (FIG. 1) is driven in from the rear face 11 (FIG. 2) so as to be inaccessible when the padlock is in use. The left face of the plug 52 is milled flat above and below a stop lug 56 which lies in the clearance groove 50 ofthe shackle leg 18, and serves as a stop to limit outward movement of the shackle when it is released from locking position. The right face of the plug 52 is cut to the surface of a cylinder forming a continuation of the surface of the bore 32. This leaves the two bores 32 and 34 as an 8-shaped chamber for the reception of a correspondingly shaped lock core as shown in FIG. 4.

Such lock core is of the type shown in Frank E. Best U.S. Pat. No. 2,814,942. Such core comprises a body 82 of the 8-shape configuration which contains a key plug 84 in its lower lobe, operable by a key 86. The body 82 has a narrow radial flange 83 at the front adapted to be received in the counterbored groove 29 of the case when the 8-shape body is inserted in the shaped chamber formed by the bores 32 and 34 of the case 12. A retaining lug 88 projects from the side of the body 82 at the rear and is retracted by the use ofa control key in the key plug 86 to permit insertion and removal of the core from the case. When the lock core body 82 is in place in the case 12, the retaining lug 88 is projected from the body by turning the control key, and engages over one of the lugs 42 on the inside of the case to retain the lock core in place until it is removed by use of the control key. The presence of the lock core in the case 12 blocks rotation of the shackle retaining plug 52 from its bayonet-lock position and thus prevents removal of that plug from the case.

A pair of oppositely moving shackle bolts 58 and 60 are mounted flat against the inner face 44 of the upper I end wall 22. As shown in FIGS. and 6, these are identical L-shaped members, with headends 62 and inward extending legs 64. Each inward extending leg contains a transverse groove 66 having parallel side faces 67 and 68. The two legs 64 lie on opposite sides of a central longitudinal interface plane x-x in side-by-side passing relation, and the side faces 67 and 68 of the transverse groove 66 are perpendicular to that interface plane. Except for the transverse grooves 66, the bolts 58 and 60 are of solid construction, for maximum strength. In their projected positions as shown in FIGS. 3 and 5, the bolts 58 and 60 enter the grooves 20 of the toe and heel legs 16 and 18 of the shackle to positively lock that shackle in locked position.

The bolts 58 and 60 are retained in place against the flat end wall 44 by a retainer plate 70. As shown in FIGS. 1, 3 and 7, this is supported at its right end in the groove 46 in the case, supported at its opposite end by a shoulder 53 on the shackle plug 52, and held in place against retraction from the groove 46 by the upper end of the plug 52.

A throw member disc 72 is rotatably mounted in the retaining plate 70, on the axis of the central bore 32 of the lock cavity. This carries a pair of downward extending legs 74 in spaced parallel relation for engagement in mating holes in the key plug of the lock core. The disc 72 and legs 74 together form a throw member.

As shown in FIGS. 3, 5, and 6, the throw member disc 72 carries a pair of diametrically-opposite. specially-shaped drive lugs 76 on a diameter at an angle of approximately 82 from the position of the throwlegs 74.. These lugsare respectively engaged in the cross slots 66 of the two tumblers S8 and 60. When such tumblers are in locking positionas shown in FIG. 5, the drive lugs 76 lie across the interface plane x.x between the legs 64 of the two tumblersQEach drive lug76 has an external surface 78 on an are about the axis of rotation of the throw member disc 72, and this is engaged tangentially by the transverse side face 67 of the transverse groove 66, substantially at a dead center position, so that the drive lug 76 positively locks the bolt in projecting position and against retraction by externally applied forces on the bolt. Moreover, the external surface 78 of the lug 76 extends over a considerable arc, of the order of 30 or more, so that such positive locking action occurs over a considerable range of angular positions of the throw member 72. The lugs 76 extend circumferentially of the throw member disc 72 a considerable distance, and are defined at their circumferential ends by arcuate surfaces on a common circle of a diameter, less operating clearances, equal to the distance between the side faces 67 and 68 of thetransverse slots 66.

When the throw member 72 is rotated clockwise from the locking position shown in FIG. 5 to the release position shown in FIG. 6, the drive lugs 76 first move transversely past the interface plane x-x between the bolt legs 64 and againstthe inner side faces 68 of the transverse slots 66. Further rotation of the throw member 72 then retracts thebolts 58 and 60. As such rotation occurs the drive lugs 76 rotate within the cross slots 66, and turn therein to a position in which their end faces 80 fit snugly between the sidefaces 67 and 68 of those cross slots, as shownin FIG. 6. This arrangement gives positive retraction of the bolts 62, and

positive projection thereof to locking positions in the notches 20 of the shackle legs, and deadlocks the bolts in such locking position when the drive lugs 76 move to the positions shown in FIG.,5. In these positions,

rearward force applied to the bolt heads 62 will be applied at or close to a dead center position on the external surface 78 of the lugs,which surfaces are concentrio with the axis of rotation of the throw member disc 72, and there is no turning moment exerted on the throw member disc 72 which would tend to cause the throw member to rotate toward a release position.

The throw member 7274 is controlled and operated by the lock core 82 inserted in the core receiving chamber formed by the overlapping bores 32 and 34 in the of the hole 24 which receives the toe 16 of the shackle. The keeper plate 90 is conveniently secured in place by a cap screw 92, and projects laterally into a notch 94 cut in the body 82 of the lock core.

Desirably. the securely fixed lock core is utilized to provide additional support for the retainer plate 70. To this end, a filler block 96 is mounted about the legs 74 of the throw member 72-74, between the top face of the lock core 82 and the bottom face of the retainer plate 70. This is desirably a generally cylindrical block,

provided with two spaced holes 97 for the reception of the two legs 74 of the throw member. The block serves not only to support the retaining plate 70, but also to stiffen and reinforce the two spaced legs 74 to prevent them from twisting out of their plane and provide a solid and direct connection between the key plug and the throw member disc 72 and its drive lugs 76.

The operation of the padlock is as follows. With a lock core 82 in place in the case 12 either the case of FIG. 1 or that of FIG. 3 rotation of the key plug by an operating key transmits rotation through the throw member legs 74 to the throw member disc 72. As shown in FIGS. 5 and 6, this swings the drive lugs 76 from their deadlocking position shown in FIG. 5 to their release position shown in FIG. 6, and this in turn moves the bolts 58 and 60 from their locking position shown in FIG. 5 to their release position shown in FIG. 6. The shackle may then be manually retracted from its locked position shown in FIGS. 1 and 3, and its outward movement is limited by engagement of the flange 49 on the heel leg 18 with the stop 56 carried by the retainer plug 52. When it is desired to lock the padlock, the shackle is rotated to a position which aligns its two legs with the two holes 24 and 26, the bolts 58 and 60 are retracted in their position shown in FIG. 6 by operation of the key, and the shackle is then moved inward to its locking position as shown in FIG. 1. The key is then turned to advance the bolts to their locking position as shown in FIGS. 1 and 5. Desirably the key is removable only when the bolts and the throw member 72-74 are in locking position as shown in FIGS. 1 and In this locking position ofthe throw member, the drive lugs 76 lie across the interface plane x-x between the legs 64 of the two bolts 58 and 60, and present their-external cylindrical faces 78, on arcs about the center of rotation of the throw member, against the outer side faces 67 of the transverse slots in the tumblers. Those side faces 67 are normal to the interface plane, and engage those arcuate external surfaces tangentially, and those surfaces positively lock the tumblers against retraction. The side faces 67 engage the external surfaces 78 substantially on dead center or close thereto, so that there can be substantially no turning moment generated on the drive lug 76 or the throw member 72 as the result of inward force applied to either or both of the bolts 58 and 60. The bolts are thus deadlocked in locking position, and they in turn have deadlocking engagement with the legs of the shackle, so that the shackle is positively locked in place and will not be dislodged or loosened by impact forces or other forced entry attack. Moreover, as shown in FIGS. 3 and 5, each lug has portions on both sides of the interface plane xx. The portion at one side has its outer face in blocking engagement with its associated bolt, while the portion on the opposite side of the interface plane lies in a position to block retraction of the opposite bolt. For-example, if the lug 76 at the right of center in FIG. 5 were to be broken, its bolt 58 could retract only a short distance before its rear end would abut the remainingother lug 76 at the left of center in FIG. 5, and this would prevent disengagement of the bolt from the shackle.

The special lugs of the throw member are held in engagement with the bolt by the retaining plate which in turn is supported both by the shackle-retaining plug 52 and through the filler block 96 by the lock core 82 which is secured in place in its close-fitting chamber both by the usual key-operated lug 88 and by the keeper plate 90. The parts are thus all firmly supported and retained and the structure has substantially improved resistance to impact stress, including both forced-entry hammering and the bouncing which occurs in truck applications.

We claim:

1. A padlock, comprising i a case having two parallel holes for reception of the spaced legs of a shackle, and a transverse bolt slideway extending between and intersecting said holes,

a shackle receivable in said holes and having boltreceiving notches in its legs,

a pair of L-shaped bolts longitudinally slidable in said slideway between projected and retracted positions,

said bolts having head ends which in said projected position extend into said shacklenotches to secure the shackle against retraction from the case,

said bolts having inward projecting legs lying on opposite sides of an interface plane in passing side-byside relationship,-the legs having transverse slots therein for engagement by a throw. member,

a throw member rotatably mounted in said case on an axis substantially in said interface plane and having eccentric drive lugs thereon engaged in said bolt slots, 1

said lugs each having'an external surface on an are about the center of'rotation of the throw member and being movable substantially to a position intersecting said interface plane, the bolt slots having outer side faces substantially normal to said interface plane and tangent to said external lug surfaces when the throw member and bolts are in bolt projected position so as substantially to deadlock'said bolts against forced retraction.

2. A padlock as in claim 1 in which said drive lugs are defined at their circumferentially opposite ends by faces on arcs of a common circle intersected by the arc of said external surface and said transverse bolt grooves have a width substantially equal, with operating clearance, to the diameter of said common circle.

3. A padlock as in claim 1 in which each arcuate external surface has a considerable arcuate length and the drive lug has a normal locking position in which its arcuate external surface extends considerable distances in both directions from its point of tangentency with the outer side face of the slot, so as to provide a range of positions of the drive lug from said normal positions in which said deadlocking action is obtained.

4. A padlock as in claim 1 in which said bolts are mounted between an inner end face of a cavity in the case and a retainer plate mounted in said cavity, with the addition of a lock core mounted in said cavity, said throw member having a leg structure connecting the same with the lock core, and a filler block about said leg structure for supporting the bolt retainer plate from the lock core. i

5. A padlock as in claim 4 in which the throw member leg structure comprises a pair of spaced parallel legs, and said filler block is a solid block having holes therein in which the legs are closely received to reinforce said legs from twisting out of their common plane.

6. A padlock as in claim 4 in which said lock core is mounted in a cavity from the opposite end of the case from'the shackle-receiving holes, which cavity overlaps one shackle-receiving hole, and a keeper plate mounted in said one shackle-receiving hole and engaged with the lock core to secure the same in position for supporting said filler block.

7. A padlock as in claim 4 in which said shackle is of maraged steel having high toughness at cryogenic temperatures.

8. A padlock as in claim 1 in which said bolts are mounted in place by a retainer plate having one end fixed in said case, and which includes a shackleretaining plug supporting the other end of the retainer plate and blocking its disengagement'from the case, and a pin fixing the shackle-retaining plug in the case.

9. A padlock as in claim 6 in which said bolts are mounted in place by a retainer plate having one end fixed in said case, and which includes a shackleretaining plug supporting the other end of the retainer plate and blocking its disengagement from the case, and a pin fixing the shackle-retaining plug in the case.

10. A padlock comprising a case and a shackle having its legs received therein.

and at least one bolt longitudinally movable into locking engagement in a notch in the shackle,

a transverse groove in the bolt and having an outer side face,

. a throw member rotatably mounted in the case and having an eccentric drive lug disposed in said groove and arcuately movable in the plane of the groove to advance and retract the bolt,

- saidvdrive lug having an external surface on an are about the center of rotation of the throw member and movable to a position in which it is engaged by said normal outer side face of the bolt groove so as to deadlock the bolt against retraction.

11. A padlock as in claim 10 in which said drive-lug external surface extends along said are over a considerable length so as to deadlock the bolt in any of a range of angular positions of the throw member.

12. A padlock as in claim 10 in which said outer side face of the bolt is normal tothe direction of bolt movement and engages the external surface of the drive lug in a tangential relation.

13. A padlock as in claim 12 in which said lug extends circumferentially of said throw member a considerable distance and is defined at its circumferentially opposite ends by faces on arcs of a common circle intersected by the arc of said external surface, said transverse bolt groove having a width substantially equal, with operating clearance, to the diameter of said common circle.

14. A heavy-duty padlock comprising a case and a shackle with its ends received in blind holes in the case,

a lock core cavity in the opposite end of the case, a pair of bolts slidable into engagement with the shacklelegs and mounted between the end wall of said cavity and a retainer plate, a rotatablethrow member mounted in the retainer plate, a rotatable throw member mounted in the retainer plate and having elongated leg structure extending axially for interconnecting thethrow member with a lock core, a lock core fixedin the cavity and spaced from the retainer plate, said lock core having a key plug in operating engagement with the end of said leg structurebut leaving an intermediate length thereof exposed in the space between the core and the retainer plate, and a filler block surrounding the leg structure and extending in twist-resisting relation therewith over substantially the full distance between the lock core and the retainer plate so as to support the plate-from the lock core and support the leg structure against twisting.

15. A padlock, comprising a case having two parallel holes for reception of the spaced legs ofa shackle, anda transverse bolt slideway extending between and intersecting said holes,

a shackle receivable in said holes and havingboltreceiving notches in its legs, l

a pair of bolts longitudinallyslidable in said slideway between projected and retracted positions,

said bolts having head endswhich in said projected position extend into said shackle notches to secure ing locked positions in which each lug extends across said interface plane, each lug in such positions having a portion on one side of the plane in retraction-blocking relation withone of said bolts and a portion on the opposite side of the. plane in position to block retraction of the other bolt. 

1. A padlock, comprising a case having two parallel holes for reception of the spaced legs of a shackle, and a transverse bolt slideway extending between and intersecting said holes, a shackle receivable in said holes and having bolt-receiving notches in its legs, a pair of L-shaped bolts longitudinally slidable in said slideway between projected anD retracted positions, said bolts having head ends which in said projected position extend into said shackle notches to secure the shackle against retraction from the case, said bolts having inward projecting legs lying on opposite sides of an interface plane in passing side-by-side relationship, the legs having transverse slots therein for engagement by a throw member, a throw member rotatably mounted in said case on an axis substantially in said interface plane and having eccentric drive lugs thereon engaged in said bolt slots, said lugs each having an external surface on an arc about the center of rotation of the throw member and being movable substantially to a position intersecting said interface plane, the bolt slots having outer side faces substantially normal to said interface plane and tangent to said external lug surfaces when the throw member and bolts are in bolt projected position so as substantially to deadlock said bolts against forced retraction.
 2. A padlock as in claim 1 in which said drive lugs are defined at their circumferentially opposite ends by faces on arcs of a common circle intersected by the arc of said external surface and said transverse bolt grooves have a width substantially equal, with operating clearance, to the diameter of said common circle.
 3. A padlock as in claim 1 in which each arcuate external surface has a considerable arcuate length and the drive lug has a normal locking position in which its arcuate external surface extends considerable distances in both directions from its point of tangentency with the outer side face of the slot, so as to provide a range of positions of the drive lug from said normal positions in which said deadlocking action is obtained.
 4. A padlock as in claim 1 in which said bolts are mounted between an inner end face of a cavity in the case and a retainer plate mounted in said cavity, with the addition of a lock core mounted in said cavity, said throw member having a leg structure connecting the same with the lock core, and a filler block about said leg structure for supporting the bolt retainer plate from the lock core.
 5. A padlock as in claim 4 in which the throw member leg structure comprises a pair of spaced parallel legs, and said filler block is a solid block having holes therein in which the legs are closely received to reinforce said legs from twisting out of their common plane.
 6. A padlock as in claim 4 in which said lock core is mounted in a cavity from the opposite end of the case from the shackle-receiving holes, which cavity overlaps one shackle-receiving hole, and a keeper plate mounted in said one shackle-receiving hole and engaged with the lock core to secure the same in position for supporting said filler block.
 7. A padlock as in claim 4 in which said shackle is of maraged steel having high toughness at cryogenic temperatures.
 8. A padlock as in claim 1 in which said bolts are mounted in place by a retainer plate having one end fixed in said case, and which includes a shackle-retaining plug supporting the other end of the retainer plate and blocking its disengagement from the case, and a pin fixing the shackle-retaining plug in the case.
 9. A padlock as in claim 6 in which said bolts are mounted in place by a retainer plate having one end fixed in said case, and which includes a shackle-retaining plug supporting the other end of the retainer plate and blocking its disengagement from the case, and a pin fixing the shackle-retaining plug in the case.
 10. A padlock comprising a case and a shackle having its legs received therein and at least one bolt longitudinally movable into locking engagement in a notch in the shackle, a transverse groove in the bolt and having an outer side face, a throw member rotatably mounted in the case and having an eccentric drive lug disposed in said groove and arcuately movable in the plane of the groove to advance and retract the bolt, said drive lug having an external surface on an arc about thE center of rotation of the throw member and movable to a position in which it is engaged by said normal outer side face of the bolt groove so as to deadlock the bolt against retraction.
 11. A padlock as in claim 10 in which said drive-lug external surface extends along said arc over a considerable length so as to deadlock the bolt in any of a range of angular positions of the throw member.
 12. A padlock as in claim 10 in which said outer side face of the bolt is normal to the direction of bolt movement and engages the external surface of the drive lug in a tangential relation.
 13. A padlock as in claim 12 in which said lug extends circumferentially of said throw member a considerable distance and is defined at its circumferentially opposite ends by faces on arcs of a common circle intersected by the arc of said external surface, said transverse bolt groove having a width substantially equal, with operating clearance, to the diameter of said common circle.
 14. A heavy-duty padlock comprising a case and a shackle with its ends received in blind holes in the case, a lock core cavity in the opposite end of the case, a pair of bolts slidable into engagement with the shackle legs and mounted between the end wall of said cavity and a retainer plate, a rotatable throw member mounted in the retainer plate, a rotatable throw member mounted in the retainer plate and having elongated leg structure extending axially for interconnecting the throw member with a lock core, a lock core fixed in the cavity and spaced from the retainer plate, said lock core having a key plug in operating engagement with the end of said leg structure but leaving an intermediate length thereof exposed in the space between the core and the retainer plate, and a filler block surrounding the leg structure and extending in twist-resisting relation therewith over substantially the full distance between the lock core and the retainer plate so as to support the plate from the lock core and support the leg structure against twisting.
 15. A padlock, comprising a case having two parallel holes for reception of the spaced legs of a shackle, and a transverse bolt slideway extending between and intersecting said holes, a shackle receivable in said holes and having bolt-receiving notches in its legs, a pair of bolts longitudinally slidable in said slideway between projected and retracted positions, said bolts having head ends which in said projected position extend into said shackle notches to secure the shackle against retraction from the case, said bolts having inward projecting legs lying on opposite sides of an interface plane in passing side-by-side relationship, the legs having transverse slots therein for engagement by a throw member, a throw member rotatably mounted in said case on an axis substantially in said interface plane and having eccentric drive lugs thereon engaged in said transverse slots, said lugs being movable to advance the bolts and having locked positions in which each lug extends across said interface plane, each lug in such positions having a portion on one side of the plane in retraction-blocking relation with one of said bolts and a portion on the opposite side of the plane in position to block retraction of the other bolt. 